Bought a long neglected 1986 XJ900. It runs but only on 2 cylinders. Non running pots are cold and leak from overflow pipes on nos 3 and 4 carbs. Obvious cause is float level I suppose. Checked the float level on non running carbs and they are way over the 22mm spec. When I bend the tangs on the floats to get within spec, the needle comes way out of the valve and binds on the float tang. Suggestions pls gentlemen?